1. Field of the Invention
The present invention generally relates to skis for snow vehicles. More particularly, the present invention relates to steering skis that provide improved handling for such vehicles.
2. Description of the Related Art
The use of snowmobiles and similar snow vehicles has increased in popularity in recent years. These vehicles are being used both for utilitarian purposes and for sport and recreational purposes. The vehicles typically are adapted to travel across snow and/or ice and usually include at least one forward facing ski along with a driven belt track or other propulsion mechanism, e.g., wheels.
Snowmobiles are controlled through the use of weight shifting and steering movement of the skis. Snowmobile skis typically have an elongated keel that is positioned along the bottom of the ski. Typically, in a vertical section, the ski and keel combination form a trapezoidal transverse cross-section, with the narrow side of the trapezoid facing downward, as in FIG. 5(a). In generally icy or snow-packed conditions, the keel increases the bite of the ski by extending into the ice or snow-pack. By so extending, a steering force is transmitted between the keel and the ice or snow-pack (i.e., a ski/snow force) when the rider directs the ski to the left or to the right. The force directs the snowmobile to the left or to the right. In contrast, a keel-less ski would rely on a much smaller, friction force to direct the snowmobile to the left or to the right. Such a ski would be much less responsive because the ski/snow force would be relatively small. The keel thus improves handling of the snowmobile compared to a flat, keel-less ski in such conditions.
However, where the snow is new and/or deep, the snow flows obliquely across the face of the ski and the trapezoidal keel as the snowmobile skis are turned to the left or to the right. Because the snow flows obliquely across the ski and keel, the keel may rise upward over the snow and may not enhance the handling very much in such conditions. Because the trapezoidal keel only provides limited handling improvement in these conditions, the rider has to exert more force on a handlebar, i.e., the rider has to “oversteer” the snowmobile skis, in order to achieve the desired direction of travel. This can cause the rider to become tired.